2020/10/08 by Kazuma Kunimatsu, Kunimatsu, Kazuma, Tufan Roy +17
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Heusler alloys: electronic and magnetic properties #Magnetic properties of thin films #Materials Science (cond-mat.mtrl-sci) #ZnO doping and properties
paper · pdf · doi:10.48550/arxiv.2010.03775
openalex publication_date 2020/10/08 · openalex created_date 2020/10/15 · openalex updated_date 2026/07/28
Co-rich Co1-xMnx alloys have hcp or fcc disordered phases and those ferromagnetic orderings are significantly deteriorated with increasing Mn concentration x in bulk. On the other hand, those metastable bcc phases show properties attractive to spintronics, e.g., high tunnel magnetoresistance (TMR) ratio of more than 200% (600%) at 300 K (10 K) in magnetic tunnel junctions (MTJs) with the x = 0.25 bcc alloy electrodes [Kunimatsu et al., Appl. Phys. Express 13, 083007 (2020)]. Here, we report systematic study of structure and magnetism for epitaxial thin films as well as the TMR effect in MgO(001)-barrier MTJs with electrodes comprising those bcc films. The single phase bcc Co1-xMnx(001) films were pseudomorphically grown on Cr(001) for 0.14 < x < 0.50 with a sputtering technique. The magnetization was larger than that of pure Co for x = 0.14-0.25 and deceased with further increasing x. This behavior mainly stemmed from the composition dependence of magnetic moment of Mn that exceeded 2 μB at the maximum, unveiled by X-ray magnetic circular dichroism. Correspondingly, within the range of 0.25 < x < 0.37, the TMR ratio decreased from 620% (229%) to 450% (194%) at 10 K (300 K) as x increased. We discussed the relationship between the magnetism and high TMR ratio with different x with the aid of the ab-initio band structure calculations.